/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.mpp.execution.operator.schema;

import com.google.common.util.concurrent.ListenableFuture;
import org.apache.iotdb.db.mpp.common.header.ColumnHeader;
import org.apache.iotdb.db.mpp.common.header.ColumnHeaderConstant;
import org.apache.iotdb.db.mpp.execution.operator.Operator;
import org.apache.iotdb.db.mpp.execution.operator.OperatorContext;
import org.apache.iotdb.db.mpp.execution.operator.process.ProcessOperator;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;
import org.apache.iotdb.tsfile.read.common.block.TsBlockBuilder;

import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static java.util.Objects.requireNonNull;
import static org.apache.iotdb.tsfile.read.common.block.TsBlockBuilderStatus.DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES;

public class NodePathsCountOperator implements ProcessOperator {

    private final OperatorContext operatorContext;
    private final Operator child;
    private boolean isFinished;
    private final Set<String> nodePaths;

    private final List<TSDataType> outputDataTypes;

    public NodePathsCountOperator(OperatorContext operatorContext, Operator child) {
        this.operatorContext = requireNonNull(operatorContext, "operatorContext is null");
        this.child = requireNonNull(child, "child operator is null");
        this.isFinished = false;
        this.nodePaths = new HashSet<>();
        this.outputDataTypes =
                ColumnHeaderConstant.countNodesColumnHeaders.stream()
                        .map(ColumnHeader::getColumnType)
                        .collect(Collectors.toList());
    }

    @Override
    public OperatorContext getOperatorContext() {
        return operatorContext;
    }

    @Override
    public TsBlock next() {
        while (!child.isFinished()) {
            // read as much child result as possible
            ListenableFuture<?> blocked = child.isBlocked();
            if (!blocked.isDone()) {
                return null;
            }
            if (child.hasNextWithTimer()) {
                TsBlock tsBlock = child.nextWithTimer();
                if (null != tsBlock && !tsBlock.isEmpty()) {
                    for (int i = 0; i < tsBlock.getPositionCount(); i++) {
                        String path = tsBlock.getColumn(0).getBinary(i).toString();
                        nodePaths.add(path);
                    }
                }
            }
        }
        isFinished = true;
        TsBlockBuilder tsBlockBuilder = new TsBlockBuilder(outputDataTypes);

        tsBlockBuilder.getTimeColumnBuilder().writeLong(0L);
        tsBlockBuilder.getColumnBuilder(0).writeLong(nodePaths.size());
        tsBlockBuilder.declarePosition();
        return tsBlockBuilder.build();
    }

    @Override
    public boolean hasNext() {
        return !child.isFinished() || !isFinished;
    }

    @Override
    public ListenableFuture<?> isBlocked() {
        return child.isBlocked();
    }

    @Override
    public void close() throws Exception {
        child.close();
    }

    @Override
    public boolean isFinished() {
        return isFinished;
    }

    @Override
    public long calculateMaxPeekMemory() {
        // todo calculate the result based on all the scan node; currently, this is shadowed by
        // schemaQueryMergeNode
        return Math.max(2L * DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES, child.calculateMaxPeekMemory());
    }

    @Override
    public long calculateMaxReturnSize() {
        return Math.max(DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES, child.calculateMaxReturnSize());
    }

    @Override
    public long calculateRetainedSizeAfterCallingNext() {
        return DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES + child.calculateRetainedSizeAfterCallingNext();
    }
}
